School of Chemistry and Chemical Engineering, Chongqing University of Science and Technology, Chongqing, 401331, China.
School of Life Science, Southwest University, Chongqing, 400715, China.
Plant Physiol Biochem. 2024 May;210:108656. doi: 10.1016/j.plaphy.2024.108656. Epub 2024 Apr 23.
Squamosa Promoter Binding Protein-Like (SPL) plays a crucial role in regulating plant development and combating stress, yet its mechanism in regulating resistance to Cd toxicity remains unclear. In this study, we cloned a nuclear-localized transcription factor, NtSPL4a, from the tobacco cultivar TN90. Transient co-expression results showed that miR156 significantly reduced the expression of NtSPL4a by binding to the 3'-UTR of its transcript. We obtained transgenic tobacco overexpressing NtSPL4a (including the 3'-UTR) and NtSPL4aΔ (lacking the 3'-UTR) through Agrobacterium-mediated genetic transformation. Compared to the wild type (WT), overexpression of NtSPL4a/NtSPL4aΔ shortened the flowering time and exhibited a more developed root system. The transgenic tobacco showed significantly reduced Cd content, being 85.1% (OE-NtSPL4a) and 46.7% (OE-NtSPL4aΔ) of WT, respectively. Moreover, the upregulation of NtSPL4a affected the mineral nutrient homeostasis in transgenic tobacco. Additionally, overexpression of NtSPL4a/NtSPL4aΔ effectively alleviated leaf chlorosis and oxidative stress induced by Cd toxicity. One possible reason is that the overexpression of NtSPL4a/NtSPL4aΔ can effectively promote the accumulation of non-enzymatic antioxidants. A comparative transcriptomic analysis was performed between transgenic tobacco and WT to further unravel the global impacts brought by NtSPL4a. The tobacco overexpressing NtSPL4a had 183 differentially expressed genes (77 upregulated, 106 downregulated), while the tobacco overexpressing NtSPL4aΔ had 594 differentially expressed genes (244 upregulated, 350 downregulated) compared to WT. These differentially expressed genes mainly included transcription factors, metal transport proteins, flavonoid biosynthesis pathway genes, and plant stress-related genes. Our study provides new insights into the role of the transcript factor SPL in regulating Cd tolerance.
富含亮氨酸重复序列蛋白 SPL 样（SPL）在调节植物发育和抵御胁迫方面起着至关重要的作用，但它在调节对 Cd 毒性的抗性方面的机制尚不清楚。本研究从烟草品种 TN90 中克隆了一个核定位转录因子 NtSPL4a。瞬时共表达结果表明，miR156 通过结合其转录本的 3'-UTR，显著降低了 NtSPL4a 的表达。我们通过农杆菌介导的遗传转化获得了过表达 NtSPL4a（包括 3'-UTR）和 NtSPL4aΔ（缺失 3'-UTR）的转基因烟草。与野生型（WT）相比，过表达 NtSPL4a/NtSPL4aΔ缩短了开花时间，根系更加发达。转基因烟草的 Cd 含量显著降低，分别为 WT 的 85.1%（OE-NtSPL4a）和 46.7%（OE-NtSPL4aΔ）。此外，NtSPL4a 的上调影响了转基因烟草中的矿物质营养稳态。此外，过表达 NtSPL4a/NtSPL4aΔ有效缓解了 Cd 毒性引起的叶片黄化和氧化应激。一个可能的原因是，过表达 NtSPL4a/NtSPL4aΔ可以有效地促进非酶抗氧化剂的积累。我们对转基因烟草和 WT 进行了比较转录组分析，以进一步揭示 NtSPL4a 带来的全局影响。与 WT 相比，过表达 NtSPL4a 的烟草有 183 个差异表达基因（77 个上调，106 个下调），而过表达 NtSPL4aΔ的烟草有 594 个差异表达基因（244 个上调，350 个下调）。这些差异表达基因主要包括转录因子、金属转运蛋白、类黄酮生物合成途径基因和植物应激相关基因。我们的研究为转录因子 SPL 在调节 Cd 耐受性方面的作用提供了新的见解。
